Invention relates to the equipment for treatment of materials in a liquid under high pressures and temperatures and can be used most efficiently in curing, polymerization, densification and chemical treatment of discrete and continuous materials under pressures above. The 10 MPa and temperatures above 100xc2x0 C.
Isostatic pressing technology is considered as one of the xe2x80x9chigh technologiesxe2x80x9d and is rapid developing in the world.
There is a known isostatic press (see the prospectus of VNIIMETMASH xe2x80x9cMachines for Powder Metallurgyxe2x80x9d, published in Moscow by Vneshtorgizdat, 1990, edition No. 763MB, p.5) that includes a pressure vessel with a working chamber.
The working chamber is hermetically sealed by the top and bottom closures that form a closed hermetic work volume in which the treated product is placed.
The treatment of the product is achieved by feeding the working liquid under the required pressure into the vessel.
The shortcoming of this isostatic press is that the process takes place at the ambient temperature since, owing to its design""s peculiarity, it cannot be equipped with a heater. The cause of it is that the vessel is filled with a liquid. This reduces the technological capabilities of such press.
Moreover, the working liquid itself, by acting on the treated product, gets into direct contact with the inner walls of the pressure vessel and causes their corrosion. All this has a negative effect both on the quality of the treated product and on the durability of pressure vessel due to the aggressive influence of the applied liquid on the inner surface of the pressure vessel. In some cases such influence leads to leakage and, furthermore, to the liquid""s breaking through into the working medium and its contamination.
The closest to the claimed invention is the cold isostatic press for treatment of materials in liquid (see the prospectus of ASEA, Sweden, A08-4007E, 1990, p. 3) which comprises a multi-cylinder pressure vessel with coaxial tightly fitted one-piece metal cylinders, whereof the outer cylinder has a tightly wound flat steel wire on its surface and the inner cylinder forms a working chamber which is hermetically closed by the top and bottom closures with seals and connected to a liquid source that creates a pressure in the vessel. The working liquid is fed under pressure directly into the vessel where the treated product is placed.
This prototype cold isostatic press has the same shortcomings as the one described before. Moreover, the liquid leakage from the vessel causes a rapid pressure drop in it (due to small compressibility of the liquid) which leads to disruption of the normal technological process.
The claimed invention is aimed at expanding the technological capabilities of isostatic pressing in isostatic presses.
The technical result of the claimed invention consists in making use of the advantages of a gas as a pressure-creating medium while subjecting the product to the action by a liquid. Both gas (mainly inert gas) and specially chosen liquids are used as working medium. Thereby the treating (forming) effect on the product is achieved by the liquid and the pressure is conveyed to the liquid through the gas medium. Owing to high compressibility of the gas medium, the pressure in the vessel is falling not so intensively during gas leakage than when a liquid is used as a pressure medium. Overall power consumption is lowered, the environmental effect is improved, the materials consumption and the dimensions of the apparatus in general are reduced.
The technical result is achieved as the isostatic press for treatment of materials in a liquid, comprising a pressure vessel which forms a hermetically sealed working chamber connected to the pressure source wherein an open-top container for liquid is placed in such a way that a gap between the inner wall of the pressure vessel and the outer wall of the container for liquid is created, whereby the container for liquid has a hermetically sealed bottom made of a current-conducting material and is placed on an electrically insulated inductive heater mounted on the protective magnetic block, while the pressure source is a gas source.
Thereby the pressure vessel is preferably made as a multi-cylinder unit with coaxial tight-fitting one-piece metal cylinders, whereof the outer cylinder is made with a tightly wound prestressing flat steel wire and the working chamber is hermetically sealed by the top and bottom closures with seals.
Thereby the protective magnetic block is located on the upper butt of the bottom closure.
Thereby the apertures for inlet-outlet of cooling water can be made on the surface of one of the one-piece metal cylinders forming the pressure vessel while a ring groove for condensate collection can be made on the butt of the bottom closure.
The electrically insulated heater can be either in the form of a flat inductor consisting of one-piece units of current-conducting (e.g. copper) plates, or in the form of a single-piece spiral-like copper plate. The protective magnetic block can be made of radial and non-contiguous units of electrical steel sheet.
Due to high compressibility of the gas medium, the pressure in the vessel during gas leakage (which is more or less inevitable) is falling not so intensively as in the case when a liquid medium is used as pressure source, thus enabling to reduce the energy cost for maintaining the normal technological process. Thereby any leakage of working liquid is excluded, what will have a beneficial ecological effect on the environment. Both the materials consumption and the dimensions of the apparatus are generally reduced.
The presence of a gas-containing volume allows to place in the vessel a heater that transfers the heat directly to the working liquid in the container, and to treat the product at high temperatures. The protective magnetic block prevents the bottom of the working chamber from induction heating thus allowing to reduce the convection in the gas volume and to lower the heat loss caused by the convection.